Marker post and manufacturing method

ABSTRACT

A marker post includes a tubular barrel with upper and lower ends and a bore extending therebetween. An annular flange assembly is formed at the barrel lower end and includes a concave extension portion extending radially outwardly from the barrel and a return portion extending upwardly and inwardly from the extension portion. The flange assembly resists pullout of the marker post when embedded in the ground. A method of manufacturing the marker post includes steps of preheating the tubular barrel adjacent to its lower end to soften same, and deforming the tubular barrel lower end to form the flange assembly thereof. An apparatus for manufacturing the marker post includes a warming tank for immersing the barrel lower ends in heated liquid for softening same. A barrel holder receives the pre-softened tubular barrels and includes a mandrel assembly reciprocated into and out of engagement with the barrel lower ends. The mandrel assembly reshapes the barrel lower ends into the flange assemblies.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to markers, and inparticular to a terrestrial marker post adapted for locating buriedutility lines and the like, and a method and apparatus for manufacturingsame.

[0003] 2. Description of the Prior Art

[0004] Marker posts are commonly used for marking the locations ofvarious underground objects. For example, utility lines are oftenburied. In many locations utility lines are required to be placedunderground for aesthetic reasons.

[0005] In recent years fiber-optic cable networks have been installed inmany parts of the country. A common installation procedure involvestrenching or boring underground and placing the fiber-optic cableswithin protective plastic conduit. The fiber-optic cables have manyadvantages for telecommunications, including the ability to efficientlytransmit large amounts of data. However, the potential earnings lossesassociated with an inoperative fiber-optic cable can be very large,because relatively high revenues are commonly generated from theirtransfer of correspondingly large amounts of data for telecommunicationscustomers.

[0006] Excavating equipment and operations pose significant threats toburied utility lines, including fiber-optic cables. Natural gaspipelines, for example, pose an explosion risk. Electrical power lineshave attendant risks of damage and injuries related to electrical power.Accidentally severing a buried fiber-optic cable can subject anexcavation contractor to significant liability for interrupted service.

[0007] In order to control such risks, utility companies and serviceproviders have marked the locations of their underground lines andprovided information regarding same, such as toll-free numbers, whichexcavators are encouraged to “call before digging”. A commonpre-existing type of marker includes a length of plastic pipe with oneend embedded in the ground and the other end mounting a cap. The cap canhave printed thereon warning information, and can be color-coded for thetype of buried utility, e.g.: blue—water; yellow—natural gas;red—electric; orange (white)—fiber-optic, etc. Such utility markers tendto be relatively effective and are widely recognized. Another advantageis that they are relatively easy to install, but unfortunately many ofthe prior art designs were easily removed. For example, the surroundingsoil can often be loosened by manipulating the above-ground portion of amarker post. The prior art marker posts were thus susceptible tovandalism, theft, etc. A previous solution to this problem involvedextending a peg through the embedded portion of the marker post and intothe surrounding soil for pullout resistance. However, the pegs and theirreceivers represented additional components and installation steps, thusadding to the installed costs of the marker posts. Moreover, installingthe pegs was sometimes overlooked whereby the marker posts wereunprotected.

[0008] Heretofore there has not been available a marker post andmanufacturing method with the advantages and features of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a vertical, cross-sectional view of a marker postembodying the present invention.

[0010]FIG. 2 is an enlarged, fragmentary, cross-sectional view thereof,taken generally within circle 2 in FIG. 1.

[0011]FIG. 3 is a further enlarged, fragmentary, cross-sectional viewthereof, taken generally within circle 3 in FIG. 2.

[0012]FIG. 4 is a perspective view of a warming tank used in thepractice of the method of the present invention.

[0013]FIG. 5a is a top plan view of a barrel holder used in the practiceof the method of the present invention.

[0014]FIG. 5b is a fragmentary, top plan view of the barrel holder,particularly showing a mandrel plug thereof advancing into the lower endof the tubular barrel.

[0015]FIG. 5c is a fragmentary, top plan view of the barrel holder,particularly showing the mandrel plug fully advanced into the barrellower end.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 1. Introduction and Environment.

[0017] As required, detailed embodiments of the present invention aredisclosed herein; however, it is to be understood that the disclosedembodiments are merely exemplary of the invention, which may be embodiedin various forms. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as abasis for the claims and as a representative basis for teaching oneskilled in the art to variously employ the present invention invirtually any appropriately detailed structure.

[0018] Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. For example,“up” and “down” refer to the invention as oriented in FIG. 1. The words“inwardly” and “outwardly” refer to directions toward and away from,respectively, the geometric center of the embodiment being described anddesignated parts thereof. Said terminology will include the wordsspecifically mentioned, derivatives thereof and words of a similarimport.

[0019] Referring to the drawings in more detail, the reference 2generally designates a marker post embodying the present invention.Without limitation on the generality of useful applications of theinvention, the marker post 2 is shown over a buried fiber-optic cable 4,which is run through buried plastic conduit. The marker post 2, beinghollow, is optionally adapted to receive a length of conduit 6containing conductors 8, which can be capped or temporarily terminated(e.g., with wire nuts 10 as shown) for future splicing in connectionwith a future transformer location or an expansion or extension ofutility services.

[0020] II. Marker Post 2.

[0021] The marker post 2 includes a tubular barrel 12 with a bore 14extending between and open at upper and lower ends 16, 18. The tubularbarrel 12 can comprise any suitable thermoplastic material, such aspolyethylene, and is formed with a sidewall 20 having interior andexterior surfaces 20 a, b.

[0022] An annular flange assembly 22 is formed at the tubular barrellower end 18 and includes an extension portion projecting radiallyoutwardly from the tubular barrel lower end 18. As shown in FIG. 3, incross section the extension portion 24 curves through slightly more than180 degrees, and displays a concave configuration. An annular returnportion of the flange assembly 22 extends upwardly and radially inwardlyfrom the extension portion 24, and terminates at a flange assembly rim28. An upwardly-open, annular channel or groove 30 is formed between thetubular barrel outer surface 20 a and the return portion 26, and isupwardly-open at an annular channel clearance 32. The channel 30 isclosed at its lower end by the flange assembly extension portion 24. Theconfigurations of the flange assembly 22 and the channel 30 formedthereby tend to resist pull-out of the implanted marker post 2.

[0023] A cap 34 is provided for conveying information, which can beprinted thereon and typically comprises a warning such as “WARNINGBURIED FIBER OPTIC CABLE IN THIS VICINITY”, together with graphicwarnings, contact information such as toll-free numbers, which can becalled for additional information, etc. The cap 34 has a closed upperend 36, which can generally be configured like a hemisphere, and an openlower end 38. The cap 34 telescopically receives through its open lowerend 38 the tubular barrel 12 adjacent to its upper end 16. The cap 34can comprise any suitable material, such as a suitable thermoplasticadapted to receive printing thereon by any suitable technique, such assilkscreening.

[0024] In operation, the marker post is adapted for embedding in soil toa sufficient depth (generally about 1 to 2 feet), as shown in FIG. 1.Power augers, post hole digger and other suitable digging tools can beused for digging a hole 40 to receive the marker post 2. The hole 40 ispreferably sized to accommodate the flange assembly 22, i.e. slightlyoversized with respect to the tubular barrel 12. The concaveconfiguration of the flange assembly 22 facilitates inserting the markerpost 2. Moreover, this concave configuration, with the correspondingcurved cross-sectional configuration, provides considerable structuralstrength for the flange assembly 22. The marker post 2 is inserted intothe hole 40 to refusal, whereat a substantial portion of its length isleft aboveground. The surrounding soil 42 is then backfilled around thetubular barrel 12, and occupies the channel 30 for engagement by theflange assembly 22 whereby the marker post 2 effectively resistspullout. The upwardly-open configuration of the channel 30 tends toresist pullout throughout the embedded length of the tubular barrel 12.Thus, even lifting the marker post 2 somewhat out of the hole 40 willnot cause it to release. Rather, the configuration of the flange islikely to cause the marker post 2 to continue to resist pullout, thushopefully discouraging its unauthorized removal.

[0025] III. Manufacturing Method and Apparatus.

[0026] Without limitation on the generality of useful methods andapparatus for manufacturing the marking post 2, an exemplary method isdescribed using a manufacturing apparatus 52, as shown in FIGS. 4, 5a, 5b and 5 c.

[0027]FIG. 4 shows a warming tank 54 with an open-top vessel 56 mountinga grid 58, which provides multiple barrel receivers 58 a adapted formaintaining the tubular barrels 12 in upright positions. Lower portionsof the tubular barrels 12 are immersed in heat transfer liquid 60, whichis heated by a thermostat-controlled heater 62 mounted on the vessel 56.The heat transfer liquid 60 can include glycol or some other suitablecomponent to raise its boiling temperature. The polyethylene tubularbarrels 12 soften and become pliable at about 165 degrees Fahrenheit, sothe heat transfer liquid 60 temperature can be maintained in the rangeof approximately 185 degrees to 200 degrees Fahrenheit for effectivepreheating of the tubular barrels 12 to a softened, pliable temperature.

[0028]FIGS. 5a-c show formation of the flange assembly 22 on a clampingbarrel holder 64, which includes first and second ends 66, 68 withrespective split sleeves 70 each comprising a fixed or lower half 72 anda movable or upper half 74. Each upper sleeve half 74 is hingedlymounted on a respective lower sleeve half 72 and is raised and loweredwith respect thereto between open and closed positions by a handle 75.Latching mechanisms 76 are provided for locking the respective sleeves70 in their closed positions.

[0029] A mandrel assembly 78 is located at the barrel holder second end68 and includes a slide subassembly 80 slidably movable between extendedand retracted positions (FIGS. 5a and 5 c respectively) by a linearactuator, comprising a piston-and-cylinder unit 81. Without limitationon the generality of useful linear actuators, a double-acting pneumaticpiston-and-cylinder unit is shown and is adapted for connection to acompressed air source 77 through a three-way valve 79. The valve 79 canincluding a lever for manual operation, a foot pedal for foot operation,a solenoid for electrical operation, etc. The linear actuator 82 isshown in its retracted position in FIG. 5a, with a mandrel plug 82thereof generally aligned with the barrel bore 14 and positioned inclose proximity to the barrel lower end 18.

[0030] The mandrel plug 82 is generally cylindrical with a distal end 83chamfered at 83 a to facilitate insertion into the barrel bore 14 and aproximate end 84 mounted on a mandrel base 85. The mandrel plug 82 hasan annular, convex forming rim 86 (FIGS. 5b, 5 c) located at thejunction between its proximate end 84 and the base 85. The mandrel plugforming rim 86 is adapted for engaging the softened barrel lower end 18and curving same through an angle of slightly more than 180 degrees,e.g., in the range of about 190 degrees to 220 degrees. As shown in FIG.5c, the barrel lower end 18 generally doubles back on itself intoengagement with the split sleeve 70, thus forming the flange assembly22. In this position the slide subassembly 80 and thepiston-and-cylinder unit 81 driving same are in their fully-extendedpositions. Retracting the piston-and-cylinder unit 82 retracts the slidesubassembly 80 and withdraws the mandrel plug 82 whereby the formedbarrel 12 can be removed.

[0031] It is to be understood that while certain forms of the presentinvention have been illustrated and described herein, it is not to belimited to the specific forms or arrangement of parts described andshown.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:
 1. An in-ground marker post, whichcomprises: a barrel with upper and lower ends and a bore extendingtherebetween and open thereat; an annular flange located at said barrellower end and including an annular extension portion extending generallyradially outwardly from the barrel lower end and an annular returnportion extending generally upwardly from said extension portion andterminating at an annular flange rim; said flange rim being locatedgenerally outwardly from and concentric with said barrel; and anupwardly-open annular channel formed between said barrel and saidextension portion.
 2. The marker post according to claim 1, whichincludes: said flange extension portion having a concave configuration.3. The marker post according to claim 1, which comprises thermoplasticmaterial with said annular flange being thermoset.
 4. The marker postaccording to claim 1 wherein said flange is contiguous and integral withsaid barrel.
 5. The marker post according to claim 1 wherein said flangereturn portion extends axially upwardly and radially inwardly from saidextension portion.
 6. The marker post according to claim 1 wherein saidbarrel and said flange comprise polyethylene.
 7. The marker postaccording to claim 1, which includes a tubular cap mounted on saidbarrel upper end, said cap including a closed upper end and an openlower end telescopically receiving said barrel.
 8. The marker postaccording to claim 7 wherein said cap upper end has a hemisphericalconfiguration, said cap includes warning and contact information printedthereon and said cap is color-coded to identify a utility line buried inthe vicinity thereof.
 9. A method of making marking posts comprisingtubular thermoplastic barrels with upper ends and flanged lower ends,which method comprises the steps of: providing a barrel with first andsecond ends and a bore extending between and open at said ends; applyingheat to said barrel lower end and thereby presoftening same; restrainingsaid barrel along the length thereof against axial movement; providing amandrel with a base, a mandrel plug mounted on and projecting generallyperpendicularly from said base and an annular transition between saidbase and said plug; providing said transition with a concave, curvedconfiguration; providing a linear actuator with extended and retractedpositions; mounting said mandrel on said linear actuator in alignmentwith said barrel bore; placing said linear actuator in said retractedposition; advancing said linear actuator axially to its extendedposition; telescopically advancing said mandrel plug into said barrelbore; engaging said barrel first end with said mandrel transition;deforming said barrel first end in a first, radial outward direction byadvancing said mandrel into said barrel bore and thereby forming abarrel end extension portion; further deforming sand barrel first end ina direction generally axial with respect to said barrel and radiallytowards same; and maintaining an upwardly-open channel formed by aspacing between said flange rim and said barrel.
 10. The methodaccording to claim 8, which includes the additional steps of: formingsaid barrel from a thermoplastic material; and heating saidthermoplastic material to a predetermined temperature at which saidmaterial becomes sufficiently soft for reshaping same.
 11. The methodaccording to claim 9, which includes the additional steps of: placingsaid marker post at a buried electrical power line location; extending aconduit from said buried electrical power line into said bore; extendingelectrical power leads through said conduit and into said bore; andterminating said power lead with insulators within said bore.
 12. Anapparatus for manufacturing a marker post with a thermoplastic tubularbarrel and a flange assembly located at one end thereof, which apparatusincludes: a warming tank including a vessel and a grid mountedthereover, said grid including multiple openings each adapted to receivea respective tubular barrel whereby said tubular barrels are preheatedand softened at respective ends thereof; said warming tank furtherincluding a volume of liquid in said vessel and including a substanceraising the boiling temperature thereof; said warming tank including aheater mounted on said vessel and adapted for heating the liquidtherein; a barrel holder including: a sleeve adapted for securing saidbarrel; a latch mechanism adapted for securing said sleeve in a closedposition thereof; a mandrel assembly including a mandrel plug with adistal end adapted for insertion into said barrel and a proximate endincluding a concave forming rim adapted for forming extension and returnportions of said preheated barrel end; a slide subassembly movablebetween extended and retracted positions with said mandrel plug extendedinto said tubular barrel bore and retracted therefrom respectively; anda piston-and-cylinder unit adapted for extending and retracting saidslide subassembly.